By Luke Pachymuthu and Manash Goswami SINGAPORE | Sun Oct 14, 2012 5:10pm EDT SINGAPORE (Reuters) - What jobs offer the highest pay? Investment banking is up there. So is specialist surgery. But consider this. Slightly over twenty years ago, Johnathan Roberts started work on an oil rig at $5 an hour. Today, the newly appointed operations manager of Norway's Standard Drilling makes about half a million dollars a year. Even accounting for inflation, it's a huge jump for the 45-year-old American. Salaries on oil rigs have soared because of a global boom in offshore drilling. Managers and workers are scarce in this specialized industry, where the work is intense and the job involves living on a platform in remote seas for weeks. For new players in Asia, where the energy demands of booming economies are driving a foray into offshore drilling, the costs and availability of skill...